Paracyclophanes. Part 58 [1]. On the Use of the Stilbene-Phenanthrene Photocyclization in 2.2]Paracyclophane Chemistry

• Autorzy: Hopf H. , Hucker J. , Ernst L.
• Języki publikacji: EN

Abstrakty

EN

The application of the stilbenephenanthrene photocyclization to [2.2]paracyclophane chemistry has been investigated. For the model system 4-styryl[2.2]paracyclophane (2) to [2.2]phenanthrenoparacyclophane (3) the reaction allows the introduction of alkyl substituents in the 6-, 7-, 8- and 9-position of the phenanthrene moiety. However, when the substituent in the 9-position (bay area of phenanthrene nucleus) becomes too large, viz. tert-butyl, no ring closure is observed anymore. The side products of the process (ring cleavage products of the cyclophane core such as 9 and 10) have been characterized for the first time. Extension of the condensed deck is possible leading to PAH-phanes as demonstrated by the preparation of the chrysenophanes 45 and 60; the cyclization to novel helicenophanes such as 50 also takes place without difficulties. In the case of 1,2-di- (4-[2.2]paracyclophanyl)ethene (63) the triply-layered hydrocarbon 65 is produced on irradiation in small amounts.

Słowa kluczowe

EN

photocyclization; condensed aromatic systems; reactions mechanisms; cyclophanes/layered molecules/stilbenes

• Wydawca: Polskie Towarzystwo Chemiczne
• Czasopismo: Polish Journal of Chemistry
• Rocznik: 2007
• Tom: Vol. 81, nr 5-6
• Strony: 947--969
• Opis fizyczny: Bibliogr. 22 poz., rys.

Twórcy

autor

Hopf H.

autor

Hucker J.

autor

Ernst L.

• Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany,

Bibliografia

• 1. For Part 57 of our cyclophane series: see Bondarenko L., Hentschel S., Greiving H., Grunenberg J., Hopf H., Dix L, Jones P.G. and Ernst L., Chem. Eur. J., in press (2007).
• 2. For the most recent monograph on cyclophane chemistry see R. Gleiter, H. Hopf (eds.), Modern Cyclophane Chemistry, Wiley-VCH, Weinheim, 2004 and references to the review literaturę cited therein.
• 3. Stilbene 2 is obtained conveniently by first formylating l and then carrying out a Wittig-Horner reaction with the produced 4-formyl[2.2]paracyclophane: Hopf H., Młynek C., El-Tamany S. and Ernst L., J. Am.Chem. Soc., 107, 6620 (1985).
• 4. Aly A.A.,Hopf H., Ernst L., Eur. J. Org. Chem., 3021 (2000). The cyclophane 8 may be regarded as a helicene into which a molecular step has been incorporated. For the preparation of the first helicenophanes see Tribout J., Martin R.H., Doyle M. avd Wynberg H., Tetrahedron Lett., 2839 (1972);cf. Nakazaki M., Yamamoto K. and Maeda M., J. Org. Chem., 46, 1985 (1981) and references cited therein.
• 5. Rozenberg V., Sergeeva E. and Hopf H., in R. Gleiter, H. Hopf (eds.), Modern Cyclophane Chemistry,Wiley-VCH, Weinheim, 2004, pp. 435-462; cf. Gibson S.E. and Knight J.D., Org. Biomol Chem., l, 1256(2003).
• 6. Lauterwasser F., Nieger M., Mansikkamaki H., Nattinen K. and Brase St., Chem. Eur. J., 11 , 4509 (2005) and refs. quoted therein.
• 7. Pye P. J., Rossen K., Reamer R. A., Tsou N.N., Volante R.P. and Reider P. J., J. Am. Chem. Soc. ,119, 6207.                 
• 8. Cram D.J. and Helgeson R.C., J. Am. Chem. Soc., 88, 509 (1966).
• 9. The strain energy of [2.2]paracyclophane (1) amounts to ca. 30 kcal/mol: Cyclophanes (P.M. Keehn, S.M. Rosenfeld, eds.), Academic Press, New York, 1983, Vol. I, pp. 34-36; cf. NishiyamaK., Sakiyama M., Sęki S., Horita H., Otsubo T. and Misumi S., Tetrahedron Lett., 3739 (1977).
• 10. According to ref. [8] the formation of side products during the photolysis of [2.2]paracyclophane takes place via triplet intermediates. In an attempt to reduce these side paths we have added biacetyl in several experiments to the photolysis mixture to ąuench these triplet states. This appears to be the case: although side product formation is not stopped completely, it is reduced significantly and the amount of the isolated phenanthrene increases by ca. 10%. So far, no systematic efforts have been undertaken to optimize this effect, e. g. by finding the optimum triplet energy of the sensitizer.
• 11. Jones P.G., Hopf H. and Hucker J., Z. Kristallogr., 209, 367 (1994).
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• 13. Review articles on the stilbene->phenanthrene photocyclization: a) Laarhoven W.H., Reel. Trav. Chim. Pays Bas, 102, 185 (1983); b) Mallory F.B. and Mallory C. W., Org. Reactions, 30, l (1984).
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• 21. Autorenkollektiv, Organikum, VEB Deutscher Verlag der Wissenschaften, 15th ed., Berlin, p. 215 (1984).
• 22. Hopf H. and Eltamany S.H., Tetrahedron Lett., 21, 4901 (1980)